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1 2003

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Teoretyczne aspekty zjawiska adhezji

Krasowska M., Jańczuk B., Wójcik W.

Wiadomości Chemiczne

2003

[Z] 57, 3-4

155--184

This paper reviews the most important problems of interparticle interactions, which determine effectiveness of many technologies (such as: painting, printing, xerographing) and physical phenomenon (for example: flocculation, aggregation, agglomeration, coagulation and wetting). This paper presents an evolution of theoretical models of adhesion phenomena. Hertz at the end of XIX century investigated creation of the contact between two particles. He based his conclusion on mechanical side of phenomena only. This observation gave beginning for Griffith's testing, which elaborated theory of brittle fracture (1920). In this theory he coupled surface energy g and elasticity. At the thirties Bradley and Derjaguin presented independently adhesion induced deformation. Bradley based his investigation on expotential relationship interaction between two molecules. Derjaguin interpreted these phenomena with the aid of geometrical and thermodynamical analysis. The fifties there was a great development of trybology and fracture mechanics. Irwin introduced new technical term of strain energy G released when the crack area varied by dS. After that Krupp generalized Derjaguin model and added influence of plastic deformation. At the early seventies two theories were created. First theory created by Johnson, Kendall and Roberts (called JKR), and second one by Derjaguin, Muller, Toporow (called DMT theory). These two models were and still are base to interpreting interparticle interactions. The next model is Dugdale model developed for crack tip plasticity and is quite simple: the stresses in the cohesive zone are constant and equal to the yield stress of the testing material. In 1983 Muller assuming a Hertzian profile, compared his earlier thermodynamic method, in which the force of attraction decreases from 2πWA to πWA, for more correct value by summing up the interactions in the Hertzian fixed gap. In this publication range of application each of these theories are introduced.